[time-nuts] Modulation Domain Analysis

Robert Gilchrist Huenemann bobgh at razzolink.com
Tue Jun 16 15:54:56 EDT 2015

I stumbled onto the time nuts list from a posting on modulation domain analysis a couple of weeks ago. I am enjoying the discussion.

I want to comment on modulation domain analysis, or phase digitizing. This is a technique that uses a period mode frequency counter, or two such counters back to back, to recover the modulation history of a frequency modulated waveform.

This technique was first used in the HP9540 automated transceiver test system. This system was described in the August 1973 HP Journal. The HP9540 used a single HP5326 period mode counter with a 10 MHz clock. At that time, no counter was available with a higher clock frequency. 

A breadboard system was assembled as part of the HP9540 development effort which used two HP5326 counters back to back. To insure that alternate periods were measured, the second HP5326 ran off the gate output of the first. However, it was realized that the characteristics of the HP9540 and its specific application were such that two counters were not required. Please refer to my HP Journal article for details.

The HP9540 was developed at HP's Automatic Measurement Division. This division was disbanded in 1974.

Modulation Domain Analysis and Phase Digitizing were terms that came into use with the later development of specialized stand alone instruments that combined computational capability, back to back period mode counters, higher clock frequencies, interpolation and algorithms for various measurements. All of these were worthwhile improvements on the basic technique first used in the HP9540.

I would be happy to answer questions. Thank you for allowing me to post this information.

Robert Gilchrist Huenemann, M.S.E.E.
120 Harbern Way
Hollister, CA 95023-9708
bobgh at razzolink.com
Extra Class Amateur Radio License W6RFW
IEEE Life Member 01189471

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